Shigella flexneri and other Shigella species represent a major cause of diarrheal diseases in developing countries (Keusch, G. T. and M. L. Bennish. 1991. in Evans AS and Brachman PS ed. Bacterial Infection of Human 2nd ed. New York and London: Plenum Medical p. 593.). It has been shown that type specific protection against shigellosis can be acquired in man after infection with a wild type or attenuated bacteria (Cohen, D. et al. 1988. J. Infec. Dis. 157: 1068.; Herrington, D. A. et al. 1990. Vaccine. 8:353; Black, R. E. et al. 1987. J. Infect. Dis. 155:1260.) and there is direct evidence that anti-type-specific LPS antibodies are associated with this protection (Cohen, D. et al. 1988. J. Infec. Dis. 157:1068.; Black, R. E. et al. 1987. J. Infect. Dis. 155:1260). It is widely agreed that local mucosal immune responses, especially secretory immunoglobulins including IgA and IgG play a major role in protection against such mucosal enteric pathogens following mucosal immunization or natural exposure; serum levels of these antibodies may be a measure or marker reflecting the production of local antibodies and, as such, may also indicate or contribute to protection (Underdown, B. J. and J. M. Schiff. 1986. Ann. Rev. Immunol. 4: 389–417; Cohen, D. et al. 1988. J. Infec. Dis. 157:1068.).
Since the demonstration in 1967 (Formal, S. B. et al. 1967. Proc. Soc. Exp. Biol. Med. 25: 347–349) that parenteral immunization with live or killed shigella bacteria was ineffective in protecting against oral challenge or monkeys with shigella, the major thrust of research has focused on the use of live attenuated or genetically constructed vaccines (Formal, S. B. and M. M. Levine. in Bacterial Vaccines, pp. 167–186). The problems associated with development of successful live vaccines include the narrow window between efficacy and safety of such vaccines since their ability to cause disease and side effects can be exceedingly dose dependant. The novelty of the current approach is emphasized by the fact that results of immunogenicity and protection in established animal models of disease were achieved despite using a sub-unit, non-living vaccine delivery system that is safe for intranasal or oral delivery. While several other approaches to the problem of development of oral or intranasal vaccines to protect against mucosal diseases in the gastro-intestinal or respiratory tract have been explored, none uses the technology of the instant invention; nor have they been effective in demonstrating induction of high levels of IgA and IgG in both mucosal secretions and sera as well as protection in established animal models as is here shown.
The data herein disclosed show that the instant invention can be used as an oral or intranasal non-living sub-unit vaccine to protect against mucosal diseases of the gastro-intestinal tract such as shigellosis. In addition, since high antibody levels are induced in either the respiratory or gastro-intestinal tracts following either oral or intranasal immunization, and since protection is shown against either conjunctival or respiratory challenge, these vaccines can also be used to protect against diseases that enter the body via respiratory, ocular or gastro-intestinal routes. By logical extension of the well-known common mucosal immune system, these vaccines also will result in protection against mucosal diseases of the urogenital and auditory tracts.
Proteosomes have previously been used with peptides (U.S. patent application Ser. No. 07/642,093 filed Jan. 16, 1991 which is a Continuation of 07/065,440 filed Jun. 23,1987) and large proteins (U.S. patent application entitled “Immunopotentiating System for Large Proteins and Polypeptides” Ser. No. 07/336,952, filed 12 Apr. 1989) in vaccine development of parenteral vaccines and Zollinger et al. (U.S. Pat. No. 4,707,543; Nov. 17, 1987) have used meningoccoccal outer memebrane proteins non-covalently complexed to detoxified lipopolysaccharides or polysaccarides in parenteral vaccines. The Zollinger work, however, specifically teaches away from the instant invention since the thrust of their work emphasizes that detoxified LPS or polysaccharide can be used wheras in the instant invention, detoxified LPS, in direct contrast to the non-detoxified LPS, is entirely ineffective. Furthermore, Zollinger neither showed, claimed nor suggested that his vaccines would be effective when deliverd via the oral or intranasal route.